Question

I don’t know regular expression good enough, and I really badly have to know how to test if an input is a float number with two digits after the dot.

Thanks in advance for the help!

Answer 1

If x is number: ^\d{2}\.\d{2}$

If x is word character ^\w{2}\.\w{2}$

Good tools for Regex:

• RegExr (Online, i don’t think it is C# Regex dialect but still very useful)
• Regex Tester (Visual Studio Extension)

In my experience Regex is not hard, but the syntax is very unintuitive you really have to memorize it or have a good tool.

On the bright side there are only a couple of instructions/keywords that you need to know but there are not too many for the common usages.

I keep a small test project with Regexes so I dont have to remember them.
In the above regexes the following is done:

• ‘^’ Matches the beginning of the string, if your string can appear in the middle of a string you need to remove it and perhaps replace it with \b that matches word boundary
• \d matches number
• \w matches any word character (alphanumeric & underscore).
• {2} tells that the previous match must appear two times. There are many variations you can use here.
• \. matches the ‘.’ it needs to be escaped with ‘\’ since . is already used by Regex (one time is implicit)
• ‘$’ matches end of string (replace with \b if your string can appear in the middle of a string)